JPH10340526A - Optical disk discriminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate easily and stably recording media having different reflectance. SOLUTION: An optical disk 1 is irradiated with, for example, a laser beam from a pickup device 2, reflected light from the optical disk 1 is detected by the pickup device 2, and information is reproduced. A detected signal from this pickup device 2 is supplied to a RF amplifier 4a for CD (read only optical disk) and a RF amplifier 4b for CD-RW (rewritable optical disk) through an APC (automatic output control) circuit 3. Signals from these RF amplifiers 4a, 4b are selected by a switch 5. Further, a detected signal of a focus error(FE) from the RF amplifier 4a is supplied to a CD/CD-RW discriminated, circuit 11, and reflectance of the optical disk 1 is discriminated. A discrimination signal from this discrimination circuit 11 is supplied to a microcomputer 8 for system control. And a control signal from the microcomputer 8 is supplied to the switch 5, the RF amplifier 4a for CD and the RF amplifier 4b for CD-RW are selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc discriminator for discriminating between, for example, a read-only optical disc (CD) and a rewritable optical disc (CD-RW) and performing reproduction suitable for each optical disc. It concerns the device.

[0002]

2. Description of the Related Art For example, a rewritable optical disk (CD) can be used for a known read-only optical disk (CD).
-RW) has been proposed. In such a rewritable optical disk (CD-RW), information is recorded by:
For example, the recording is performed by using a laser light beam to change the recording material provided on the recording surface of the disk into a crystalline phase and an amorphous phase.

[0003] That is, in recording this information, a recording material that undergoes a phase change, such as Ag-In-Sb-Te, is used. By irradiating such a recording material with a controlled laser light beam, for example,
The recording material is changed into a high-reflectivity crystalline phase (erased state) and a low-reflectance amorphous phase (recorded state), and information is recorded and reproduced by a change in the light reflectance of each of these phases. Things.

Therefore, in such a CD-RW,
It is possible to rewrite the recorded information 1000 times or more, and to record the information stably with the reproduction stability of 1 million times or more. In such a CD-RW, for example, a constant recording linear velocity of 2.4 m / s enables continuous recording for 74 minutes on a single surface of a disk. For example, a recording capacity of 650 MB can be achieved by a standard recording method. What you can get.

[0005]

By the way, such C
In D-RW, recorded information is reproduced by a change in reflectance. However, in this case, the reflectance obtained by the phase change is, for example, 15 to 25% in the above-described recording material. That is, the reflectivity of the CD-RW is only about 1/4 that of the conventional CD, which is almost 100%.

Accordingly, when a disk having a low reflectance is reproduced, an RF signal as a reproduction signal, a focus error (FE) detection signal used for condensing a light beam, and a tracking used for tracking a track are used. Error (T
The output level of the detection signal and the like in E) is reduced, and normal reproduction becomes difficult in a current CD reproducing device (player) or a so-called CD-ROM reproducing device (drive).

Therefore, for example, when such a CD-RW is reproduced, measures such as increasing the gain of the RF signal reproduction amplifier and increasing the output of the laser light beam are taken in advance. However, in order to take such measures, it is necessary that the type of the disc to be reproduced is determined in advance.

On the other hand, in a conventional apparatus, there has been proposed a means for detecting the level of reflected light of a laser beam from a disk, for example, and for directly determining the reflectance of the disk. However, for example, when discriminating between the above-described CD-RW and a normal CD, the means for directly detecting the level of the reflected light of the laser light beam as described above uses, for example, when the laser light beam is out of focus. In addition, there is a high possibility that erroneous detection will occur.

The present application has been made in view of the above points, and the problem to be solved is that the conventional apparatus, for example, directly detects the level of the reflected light of a laser beam. For example, when a laser beam is out of focus, erroneous detection is likely to occur.

[0010]

Therefore, in the present invention, the level of the focus error signal of the light beam is detected to determine the recording medium. Different recording media can be easily and stably determined.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a recording medium is irradiated with a light beam from a light beam generating means, the reflected light is detected to reproduce information, and a focus error signal of the light beam is extracted. Means for determining the recording medium by detecting the level of the focus error signal when reproducing a plurality of types of recording media having different reflectances.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a main part of an example of a reproducing apparatus to which an optical disc discriminating apparatus according to the present invention is applied.

In FIG. 1, an optical disk 1 is irradiated with, for example, a laser beam from a pickup device 2, and the reflected light is detected by the pickup device 2 to reproduce information recorded on the optical disk 1. Then, a signal detected by the pickup device 2 is supplied to an automatic output control (APC) circuit 3 to take out a reproduced signal, and a signal from the APC circuit 3 is fed back to the pickup device 2 to irradiate the optical disc 1. The output of the laser light beam is controlled.

Further, the reproduced signal from the APC circuit 3 is C
It is supplied to a reproduction (RF) amplifier 4a for D and a reproduction (RF) amplifier 4b for CD-RW. In this case, C
The gain of the D-RW RF amplifier 4b is, for example, four times that of the CD RF amplifier 4a. The signals from the RF amplifiers 4a and 4b are selected by the switch 5 and supplied to the digital signal processing (DSP) circuit 6, where the DS
The signal processed by the P circuit 6 is taken out to an output terminal 7.

A microcomputer (microcomputer) 8 for system control is provided. In the microcomputer 8, signals are exchanged with the above-mentioned DSP circuit 6, and information such as a track position being reproduced is supplied to the microcomputer 8. Then, a control signal from the microcomputer 8 is supplied to a servo circuit 9 and the like, and servo control of the pickup device 2 and the spindle 10 of the disk 1, such as search for desired information and constant linear speed rotation, are performed.

Further, for example, a signal from the above-described RF amplifier 4a is supplied to a CD / CD-RW discriminating circuit 11. The discrimination circuit 11 discriminates CD / CD-RW by discriminating the level of a focus error detection signal (FE signal) from the RF amplifier 4a, for example. The discrimination signal is supplied to the microcomputer 8, and the microcomputer 8
Is supplied to the switch 5 and the above CD
Amplifier 4a for CD and RF amplifier 4b for CD-RW
Is selected.

That is, in this apparatus, the optical disk 1
Is newly installed, first the pickup device 2
The focus search operation for determining the reference position of the focal point of the condenser lens of the laser light beam is performed. Therefore, in such a focus search, the detected FE signal depends on the difference in the reflectance of the loaded optical disc 1, for example, when the optical disc 1 is a CD, the FE signal in FIG.
In the case of a CD-RW, the result is as shown in FIG.

Here, each FE signal indicates the focal point at the center 0 cross, but the peak levels before and after the FE signal change due to the difference in the reflectivity of the optical disc 1, and the optical disc 1 is in a CD-RW format. In the case of, as shown, it is lower than that of the case of CD. Therefore, the change due to the difference in the reflectance is determined based on, for example, a reference level Ref as shown in the figure, and when the peak level of the FE signal exceeds the reference level Ref during the focus search, the CD is obtained. Is determined.

FIG. 3 shows the detection of the FE signal and the CD / C
A specific example of D-RW discrimination will be described. Here, A in FIG. 3 shows a so-called quadrant (A to D) photodetector. As shown in the figure, the light detector is focused when a reflection spot (oblique line) of the laser light beam hits the center of the light detector, and when the focus shifts, for example, the reflection spot moves right and left in the drawing. It is configured to be. Therefore, at the time of the above-described focus search, the reflected spot passes through, for example, from right to left in the drawing.

For example, in the RF amplifier 4a,
Photodiodes 21A to 21D constituting a photodetector
However, as shown in FIG. 3B, photodiodes 21A and 21C and photodiodes 21B and 21D are connected in parallel, respectively. As a result, when the reflection spot hits the photodetector, these photodiodes 21A and 21C
Current is a current i ₁ is caused to flow by the addition, so that the current i ₂ flows are summed current of the photo diode 21B and 21D are.

These currents are further supplied to the amplifiers 22A and 22A.
B is supplied to the differential amplifier 23. As a result, the FE signal of K (i ₂ −i ₁ ) is extracted from the differential amplifier 23 to the output terminal 24. In this way, a focus error detection signal (FE signal) is extracted from, for example, the RF amplifier 4a. Note that K is an arbitrary coefficient in the above-described equation of the FE signal. In the above-described circuit, for example, the focus bias from the variable resistor 25 is supplied to the input of the differential amplifier 23 on the current i ₁ side.

In this circuit, when the reflection spot is passed through, for example, from right to left in FIG. 3A by the focus search, the level of the first FE signal is 0. Then, when the reflected spot starts to hit the photodetector, the current i ₂
Flows, and the signal level rises rapidly to a positive peak. Further, when the reflection spot is located at the center of the photodetector at the focal point, the current i ₂ = i _{1 and the} signal level becomes zero cross. Thereafter, the current i ₁ increases and the signal level drops sharply, and goes to zero through a negative peak.

Thus, the FE signal as shown in FIG. 2 is formed. And in this case, the above-mentioned FE
The positive and negative peak levels of the signal are changed by the reflectivity of the optical disc 1 that reflects the laser light beam. Therefore, this FE signal is supplied to the comparator 2 as shown in FIG.
6, the reference voltage Ref from the DC voltage source 27 is applied to the non-inverting input of the operational amplifier.
The peak level of the E signal is determined.

The discrimination signal is supplied to the microcomputer 8, and a control signal from the microcomputer 8 is supplied to the switch 5
And the RF amplifier 4a for CD and the CD-RW
Of the RF amplifier 4b is performed. by this,
For example, when the loaded optical disc 1 is determined to be a CD-RW, the RF amplifier 4b for the CD-RW is selected, the amplification gain of the RF signal is quadrupled, and a decrease in the reflectance of the CD-RW is compensated. , Normal reproduction is performed.

In the apparatus shown in FIG. 1, when the optical disk 1 is a CD-RW, for example, the reproduction (R
F) Control to increase the signal amplification gain by four times is performed. With this control, for example, the optical disc 1 is
Even when the reflectance becomes 25%, the level of the reflected light becomes equal to that of the CD, and a good reproduction (RF) signal, a tracking error (TE) detection signal, and a focus error (FE) are obtained. The output of the detection signal or the like can be obtained.

Accordingly, in this apparatus, the recording medium is determined by detecting the level of the focus error signal of the light beam, whereby the recording medium having a different reflectance can be easily and stably determined.

Thus, according to the present invention, in the conventional apparatus, there is a great possibility that erroneous detection will occur when the laser light beam is out of focus, for example. By detecting the level, such a problem can be easily solved.

Therefore, by employing this apparatus as, for example, a normal CD reproducing apparatus (player) or a so-called CD-ROM reproducing apparatus (drive), it is possible to easily and stably discriminate an optical disk in these apparatuses. Yes, for example, rewritable optical disc (CD-RW)
Can be satisfactorily reproduced.

Thus, according to the above-described optical disc discriminating apparatus, the recording medium is irradiated with the light beam from the light beam generating means, the reflected light is detected to reproduce the information, and the focus error signal of the light beam is extracted. Means for reproducing a plurality of types of recording media having different reflectances, by detecting the level of the focus error signal to determine the recording media, thereby easily and easily determining the recording media having different reflectances. It can be performed stably.

In the above-described apparatus, the level of the reproduction signal detected by the pickup device 2 is quadrupled by quadrupling the output of the laser beam emitted from the pickup device 2 to the optical disk 1. Can be. That is, in the above-described apparatus, for example, when the optical disk 1 is a CD-RW, the output of the laser light beam from the pickup device 2 is quadrupled by controlling the signal fed back from the APC circuit 3 to the pickup device 2. can do.

Thus, for example, if the optical disc 1 is a CD
When the reflectivity becomes 25% in -RW, the output of the laser light beam is quadrupled, so that the level of the reflected light also quadruples, and the level of this reflected light is equal to that of the CD. As a result, it is possible to obtain an output such as a good reproduction (RF) signal, a tracking error (TE) detection signal, a focus error (FE) detection signal, and the like. Even in this case, for example, a rewritable optical disk (CD-RW)
Can be satisfactorily reproduced.

FIG. 4 is a diagram showing the A used in the above-described apparatus.
An example of a specific circuit configuration of the PC circuit 3 is shown. This figure 4
, A laser diode (LD) 31 for generating a laser beam and a photodiode (PD) 32 for detecting the reflected light of the laser beam from the laser diode 31 reflected on a disk (not shown) are provided. Can be A voltage Vcc from a power supply terminal 34 is applied to one end of the laser diode 31 through, for example, an output control transistor 33.

One end of the photodiode 32 is connected to, for example, a 2.2 kΩ variable resistor 35 and a 91 kΩ resistor 3.
6 through a series circuit. The other ends of the laser diode 31 and the photodiode 32 are grounded. Further, one end of the photodiode 32 is grounded through a series circuit of, for example, a resistor 37 of 100 kΩ, a resistor 38 of 33 kΩ, and a transistor 39 for switching. The middle point of connection between the resistors 37 and 38 is R
Connected to PD terminal of F amplifier circuit 40.

Further, in the RF amplifier circuit 40, for example, a signal from a PD terminal is supplied to a non-inverting input of an operational amplifier circuit 41, and the inverting input of the operational amplifier circuit 41 is grounded through a resistor 42 of 10 kΩ. , And the output is fed back to the inverting input through the resistor 43 of 55 kΩ. The output of the operational amplifier circuit 41 is a resistor 4 of 10 kΩ.
4 to the non-inverting input of the operational amplifier circuit 45,
The non-inverting input of the operational amplifier circuit 45 is connected to a VC terminal 47 through a resistor 46 of 56 kΩ.

The inverting input of the operational amplifier circuit 45 is supplied from a battery 49 through a 10 kΩ resistor 48.
A reference voltage of 25V is provided. Further, the output of the operational amplifier circuit 45 is fed back to the inverted input through the resistor 50 of 56 kΩ. Thus, in the operational amplifier circuit 45, the signal from the operational amplifier circuit 41 is compared with the reference voltage from the battery 49. And this operational amplifier circuit 45
Is output to the LD terminal of the RF amplifier circuit 40 through the resistor 51 of 1 kΩ.

Further, a signal from the LD terminal of the RF amplifier circuit 40 is supplied to the base of the transistor 33 for output control. The transistor 33 has a base of 10
The power supply terminal 34 is connected to a power supply terminal 34 through a 0 μF capacitor 52 and is connected to a resistor 53 of 22 kΩ.
Through the collector of the transistor 33. The emitter of the transistor 33 is connected to one end of the laser diode 31.

In the circuit of FIG. 4, when the switching transistor 39 is off, the signals generated by the photodiode 32, the variable resistor 35, and the resistor 36 are passed through the resistor 37 to the RF amplifier circuit 4 as it is.
0 is supplied to the PD terminal. The potential of this signal is compared with the reference voltage from the battery 49 by the operational amplifier circuit 45 through the operational amplifier circuit 41, and a control signal is supplied to the base of the transistor 33 through the LD terminal so that the potential of the signal becomes a predetermined magnitude. Is done.

On the other hand, when the switching transistor 39 is on, the signal generated by the photodiode 32 and the like is divided by the resistors 37 and 38 and supplied to the PD terminal of the RF amplifier circuit 40. You. That is, a signal divided into approximately 1/4 is supplied to the PD terminal. Then, a control signal is supplied to the base of the transistor 33 through the LD terminal so that the potential of this signal becomes a predetermined value, so that the output of the laser diode 31 is controlled to be approximately four times as large. Will be

That is, in the circuit shown in FIG. 4, when the transistor 39 is turned on, control for making the output of the laser diode 31 approximately four times as large is performed. Therefore, in the apparatus shown in FIG.
In the case of the RW, the discrimination signal from the discrimination circuit 10 is supplied to the APC circuit 3 through the microcomputer 7 and the above-mentioned transistor 39 is controlled to be turned on, so that the output of the laser beam from the pickup device 2 becomes 4 Control for doubling can be performed.

Thus, in the apparatus shown in FIG. 1, for example, when the optical disk 1 is a CD-RW, the output of the laser light beam from the pickup device 2 is controlled to be quadrupled. With this control, for example, even when the optical disk 1 is a CD-RW and its reflectivity is 25%, the level of the reflected light becomes equal to that of a CD, and a good reproduction (RF) signal and tracking error It is possible to obtain outputs such as a detection signal of (TE), a detection signal of focus error (FE), and the like.

[0041]

According to the first aspect of the present invention, the recording medium is determined by detecting the level of the focus error signal of the light beam, whereby the recording medium having a different reflectance can be easily and stably determined. Is what you can do.

Thus, according to the present invention, in the conventional apparatus, there is a great possibility that erroneous detection will occur when the focus of the laser light beam is deviated, for example. By detecting the level, such a problem can be easily solved.

Therefore, by adopting the optical disk discriminating apparatus of the present invention, for example, as a normal CD reproducing apparatus (player) or a so-called CD-ROM reproducing apparatus (drive), it is possible to easily and easily discriminate an optical disk in these apparatuses. It can be performed stably, for example, so that it is possible to satisfactorily reproduce a rewritable optical disk (CD-RW).

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of a reproducing apparatus to which the present invention is applied.

FIG. 2 is a diagram for explaining this.

FIG. 3 is a configuration diagram of a main part circuit.

FIG. 4 is a configuration diagram of a main part circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Pickup device, 3 ... Automatic output control (APC) circuit, 4a, 4b ... Reproduction (RF) amplifier, 5 ... Switch, 6 ... Digital signal processing (DSP) circuit, 7 ... Output terminal, 8 ... Microcomputer for system control, 9 servo circuit, 10 spindle, 11 discrimination circuit for CD / CD-RW

Claims (3)

[Claims] And a means for irradiating a recording medium with a light beam from a light beam generating means, detecting reflected light to reproduce information, and extracting a focus error signal of the light beam. An optical disc discriminating apparatus characterized in that when reproducing a plurality of types of recording media different from each other, the level of the focus error signal is detected to discriminate the recording media. 2. The optical disc discriminating device according to claim 1, wherein the focus of the light beam is searched in advance, and the recording medium is discriminated by detecting a peak level of the focus error signal at the time of the search. apparatus. 3. The optical disc discriminating apparatus according to claim 1, wherein the plurality of types of the recording medium include a read-only optical disc and a rewritable optical disc.